Self-contained automated brewing and beverage dispensing devices are well known in the food and beverage industry and are commonly found in cafeterias, restaurants and coffee shops. Such dispensing devices are particularly popular in locations where patrons want freshly brewed drinks but the owner of the establishment does not have the staffing resources or the equipment and ingredients required to make them.
Most brewing and dispensing machines contain a number of dispensers for dispensing a measured quantity of a granulated food or beverage concentrate, or a beverage additive, such as sugar or flavouring, allowing users to adapt the dispensed drinks to their individual tastes. Control of dispensing volume may be an available feature of the dispensing equipment having the advantage of rendering a consistent product when a customer orders a standard order such as “one sugar” or “double sugar”, for example. In response to the user's input, such a dispenser will dispense a predetermined amount of the requested powder, thereby ensuring consistency of the final product between orders.
It is known from the prior art that the mechanics behind the dispensing of granular materials, such as powders, often involve a rotating auger member driven by a motor, whereby the auger's action causes a volume of powder to be moved to a discharge port. Augers can be of a conveyor type, most of which have a helical shaped flight along a length of a shaft with a predetermined pitch. The flight of the auger (i.e. the distance between the uprights in the auger) may be calculated to allow for moving a specific amount of powder from a hopper to a discharge port. For example, one full revolution of the auger can be calibrated to dispense the powder in a single pitch of the flight. When a full pitch is dispensed, the bottom edge of the flight is substantially positioned adjacent to the opening edge of the port, hence there is little to no non-dispensed powder remaining.
However, the hopper-and-auger combinations taught by the prior art lead to some difficulties. If the auger does not make a full revolution dispensing inaccuracies will occur. This is because the non-dispensed powder is positioned between a rear flight edge and the port and is prone to cascading in an “avalanche” effect if the machine is accidentally jostled, which is likely in most service industry environments where such a dispensing machine would be used. This is referred to as a “high-low” effect, because the first dispense operation will provide more than the desired amount of powder, while the next dispense operation will provide less than the desired amount of powder since some of it has been inadvertently dispensed in the first dispense operation.
Another issue with prior art dispensers is “dribbling” of granular material from a dispensing port. In certain prior art dispensers, undispensed power sits near the discharge port, and can fall out if the machine is jostled when not in use. If there is not a cup or receptacle underneath the outlet, the material may fall onto a counter supporting the dispenser. This can lead to wasted material and to increased expense as cleanup is required. In addition, suspended clumps may form if the material is left undisturbed for a period of time. These clumps will break apart and fall through the discharge port if the machine is jostled or bumped while not in use.
It is known in the prior art that mounting the auger at a positive angle with respect to the discharge port helps minimize “dribbling” of granular material, as gravity will force any undispensed granular material against a back surface of a flight in the auger. However, this configuration results in strain on the rear bushing as the material in the hopper will descend towards a rear portion of the hopper where the bushing is positioned that allows the auger to rotate via an externally mounted motor. More specifically, the material can cause aggressive wear on the rear bushing, thereby requiring frequent replacement and/or maintenance. Dribbling of powder may further be minimized by backdriving, or reversing the auger, for example by a ½ revolution, such that any non-dispensed powder is withdrawn from the discharge port. However, backdriving of the motor exacerbates bushing wear.
Furthermore, in some dispensers known in the prior art, powdered material to be dispensed is discharged through a vertically oriented channel. In such configurations, dispensed material strikes the sides of the channel and scatters as it exits. This is sometimes referred to as “overspray”. As a result, not all of the powdered material that is measured to be dispensed, lands in the vessel intended to receive the material and instead, lands on the counter. Thus, the accuracy of the dispense is reduced. Cleaning up of the mess on the counter leads to aggravation and expense of effort by the user, the owner, or the operator of the dispenser, and extra cost to the operator as additional staff may be needed to assist in the cleaning.
It is, therefore, desirable to provide a dispenser system for granular material that accurately dispenses fine powders and other granular materials.